EUVL Mask Absorption Layer Etching Precision
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Solution Overview
Problem
Current EUVL mask fabrication methods result in poor pattern precision due to isotropic etching of the absorption layer, leading to side etching and deterioration of the EUV beam absorption profile, which can cause shifts in the pattern on exposed wafers and potentially lead to device failures like short circuits.
Innovation Solution
A method involving alternate etching and oxidant feeding steps using a charged particle beam and halogenated xenon gas to form a side face-oxidized layer, prioritizing anisotropic etching to minimize side etching and maintain high precision in the absorption layer pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If isotropic etching with halogenated xenon gas is used to remove the absorption layer, then the etching process is simple and effective, but side etching occurs leading to poor pattern precision
Solution Approach 1:
The patent segments the etching process into multiple sequential steps: first performing isotropic etching with halogenated xenon gas to remove the absorption layer, then performing anisotropic etching to correct side etching. This segmentation allows each etching method to be optimized for its specific function, achieving both manufacturing efficiency and pattern precision.
Solution Approach 2:
The patent changes the etching parameters by switching between different etching modes (isotropic to anisotropic) and adjusting etching conditions in sequential steps. This parameter change approach allows the process to first achieve efficient material removal, then correct the side etching to restore pattern precision.
2Reliability
If ion beam irradiation with halogenated xenon gas is used for black defect repair, then over-etching is minimized, but isotropic etching still causes side etching of the absorption layer
Solution Approach 1:
The patent segments the defect repair process into two distinct phases: first using ion beam irradiation with halogenated xenon gas for effective black defect removal, then applying anisotropic etching to correct the side etching. This segmentation maintains the effectiveness of defect repair while addressing the precision issue.
Solution Approach 2:
The patent introduces anisotropic etching as an intermediary step between the isotropic etching and the final pattern formation. This intermediary process corrects the side etching caused by the isotropic etching, serving as a mediator to restore pattern precision after defect repair.
3Manufacturing precision
If side etching of the absorption layer is suppressed, then pattern precision is improved, but additional process steps are required
Solution Approach 1:
The patent segments the etching process into controlled sequential steps with specific objectives for each step. This segmentation, while adding process steps, allows for precise control of side etching and maintains pattern precision through systematic process management.
Solution Approach 2:
The patent employs parameter changes by switching between different etching modes and conditions in sequential steps. This approach manages process complexity through systematic parameter adjustment rather than requiring complex equipment or processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses side etching of the absorption layer, allowing for the fabrication of EUVL masks with high precision, thereby preventing pattern shifts and improving device performance.
Implementation Method 1
etching at least a part of the absorption layer by allowing a charged particle beam to irradiate the absorption layer under feed of a halogenated xenon gas
Implementation Method 2
chemical etching with the halogenated xenon gas is isotropic etching
Implementation Method 3
feeding an oxidant to the absorption layer after the etching step to form an oxidized layer on the absorption layer
Data Source
AI summary
A method for fabricating an extreme ultraviolet lithography (EUVL) mask. In an etching step, at least a part of an absorption layer of an EUVL mask is etched by allowing a charged particle to irradiate the absorption layer under feed of a halogenated xenon gas. In an oxidant feed step, an oxidant is fed to the absorption layer after the etching step to form an oxidized layer at a side surface of the absorption layer that is not etched during the etching step.